Pathology/Lab Coding Alert

Question: Our lab performed a basic metabolic panel (total calcium), followed by two sodium tests on the same date for a 70-year-old female patient. The patient was hospitalized following hip replacement surgery, and her initial sodium level was 115 mmol per liter, which increased progressively in the two subsequent readings. Can you explain how to get the subsequent sodium tests covered, which our payer has denied?

Texas Subscriber

Answer: You probably need to use a modifier for the subsequent sodium tests, and report an ICD-10 code that demonstrates medical necessity for the testing.

The codes for the tests you describe are 80048 (Basic metabolic panel (Calcium, total)… ) which includes a sodium blood chemistry, and 84295 (Sodium; serum, plasma or whole blood).

For repeat testing on the same date of service, you could append modifier 91 (Repeat clinical diagnostic laboratory test). Some payers prefer that you list each test on a separate claim line, or use a different modifier, such as 59 (Distinct procedural service).

Medical necessity: The patient’s initial sodium level indicates hyponatremia, which is a sodium level below 135 mmol per liter. Low blood sodium is a potentially life-threatening condition that may develop post-surgically, especially in older women. You can report the condition as E87.1 (Hypo-osmolality and hyponatremia).